1. Field of the Invention
The present invention relates to alkylated and/or aralkylated polyhydroxy aromatic compounds and to processes for their preparation and use.
2. Description of Related Art
Polyhydroxy aromatic compounds are employed, in particular, in polymer chemistry as starting materials for the preparation of polycarbonates, polyesters, polyethers, and epoxy resins. The term polyhydroxy aromatic compounds refers hereinafter to aromatic compounds having two or more hydroxyl groups in the molecule. The aromatic compounds may be mono- or polycyclic, and as structural elements may also include any desired combinations of individual and fused rings, and divalent groups such as (thio)ether bridges, carbonyl groups, sulfonyl groups, carboxamido groups, and/or alkylene groups.
Whereas, for example, the polycarbonates and polyphthalates derived from bisphenol A are readily soluble in aromatic solvents, the solubility in aromatic solvents of the epoxy resins which are conventional in industry is low or nonexistent. The aliphatic ethers which are suitable as solvents for epoxy resins, examples of which include methoxypropanol, ethylene glycol monobutyl ether, diethylene glycol dimethyl ether, on the one hand, are considerably more expensive than conventional solvents and, on the other hand, tend to form peroxides in contact with atmospheric oxygen. They are therefore more complex to handle and constitute a safety hazard.
Attempts previously have been made to obtain modified phenols by substitution of phenols with aryl radicals or aralkyl radicals. For instance, DE-A 19 40 220 describes a process for the preparation of aralkyl phenols by reacting an aromatic vinylidene compound with a phenol, with catalysis by acids or Friedel-Crafts catalysts.
Austrian Patent AT 284 444 discloses the reactions of substituted or unsubstituted styrenes with phenols. In these reactions, the vinyl group of the styrenes is added on ortho or para to the OH group of the phenol. The reaction is in general accelerated by using Friedel-Crafts catalysts, for example, acids and metal halides. Depending on the conditions, catalysts and proportions of the reactants which are employed in this reaction, mono-, di- or tristyrenized phenols are obtained. See page 1, lines 23 to 29. Under the conditions of the Friedel-Crafts reaction, however, isomerization reactions also take place. For example, in the case of the bis- or poly (hydroxyphenyl) alkanes, the bond between the aromatic compound and the alkylene group is broken under the reaction conditions, leading to isomerization reactions. Mixtures of polyhydroxy aromatic compounds with very different substitution patterns are obtained, and in some cases phenol or other highly volatile hydroxy aromatic compounds also are given off. Depending on the temperature, duration and conditions of the reaction, highly crosslinked brittle products or rubber-like, tacky products are obtained if the hydroxy aromatic compounds obtained in this way are reacted with epichlorohydrin or with diglycidyl compounds to give epoxy resins.
For the purpose of modifying phenols as starting compounds for epoxide base structures, methods of ring alkylation have been described, for example with olefins (K.-D. Bode in Houben-Weyl: Methoden der Organischen Chemie [Methods of organic chemistry], 4th edition, Vol. 6/1c, p. 955 ff., Georg Thieme Verlag, Stuttgart 1976). The preparation of epoxides therefrom is carried out, for example, as indicated in U.S. Pat. No. 4,594,398, wherein cationic alkylation of phenol with aliphatic dienes in the presence of catalysts is followed by reaction with epichlorohydrin to give the diglycidyl ether and resulting thereby in bisepoxides being obtained. By means of these substitution reactions, alkyl groups additionally are introduced without, however, improving the solubility in aromatic hydrocarbons. The reaction products are not uniform structures, but represent mixtures of polyhydroxy aromatic compounds with various substitution patterns and a varying number of hydroxyl groups in the molecule.